(1) Field of the Invention
The present invention generally relates to compounds having pharmacological activity which are useful as pharmacological agents and, more particularly, as analgesic agents for the treatment of pain, to pharmaceutical compositions containing one or more of these compounds, and to methods of treatment employing these compounds. More particularly, the present invention concerns novel opioid analgesic compounds, pharmaceutical compositions containing one or more of these compounds in combination with a pharmaceutically-acceptable carrier, and methods of treating pain employing these compounds.
Analgesic compounds are agents which alleviate pain without causing a loss of consciousness and, thus, which are useful for treating pain.
The major classes of analgesic compounds include narcotic analgesics, or opiates, compounds which alleviate pain and induce sleep, and analgesic-antipyretic compounds, compounds which alleviate pain and reduce fever, such as salicylates.
Although the efficacy of opiates in relieving pain is well established, the associated addiction liability of opiates is a distinct disadvantage of these compounds.
While salicylate and salicylate-like agents (non-steroidal antiinflammatory agents or NSAIDS) are also efficacious in relieving pain, they often exhibit undesirable side effects, such as gastrointestinal irritation, as with aspirin, allergic response, as with aspirin, and/or liver toxicity with extended use, as with acetaminophen.
The compounds of the present invention are novel opioid agonist analgesic compounds of comparable potency to morphine. The compounds have the potential for reduced side effects such as abuse potential, addiction liability, tolerance, respiratory depression or constipation, as compared to other agonists.
(2) Description of the Related Art
U.S. Pat. No. 4,816,586 issued Mar. 28, 1989, discloses delta opioid receptor antagonists of the formula ##STR2## which are described as useful for blocking delta-opioid receptors in mammalian tissue by contacting the receptors with one of the delta-opioid antagonists of the noted formulae. The antagonists are suggested for use as pharmacologic and biochemical probes of opioid receptor structure and function and for use clinically, i.e., to counteract life-threatening shock.
The document described hereinabove discloses compounds which are structurally different from the compounds of the present invention. Thus, the compounds of the present invention are structurally distinct from that which has been described in the art.